Yes, sir, it sounds like your seahorses are thriving and displaying a healthy interest in breeding. It’s sounds like what you are describing is Ed, your stallion, inflating his brood pouch to its fullest extent while courting your female, and Snowflake, your brood mare, subsequently responding to Ed’s advances and inserting her ovipositor into his pouch in order to deposit her eggs. If that’s the case, then Ed may indeed be pregnant. A good rule of thumb to go by is that if a male’s pouch remains swollen and enlarged for more than three days in a row, then chances are good that he may be pregnant rather than merely performing pouch displays. If so, Ed will be ready to deliver his brood of young in two to four weeks, depending on what species your seahorses are, and I will be happy to help you make preparations for the blessed event!
That gives you 2-4 weeks to prepare a suitable nursery tank and to begin culturing suitable live foods for the newborns. The best type of nursery tank and suitable first food for the babies depends on what type of seahorses you have, so if you can advise me as to what species Ed and Snowflake happen to be, I can provide you with better advice on how to prepare for the babies, sir.
In the meantime, I can tell you that all seahorse babies are challenging to raise and Ocean Riders are no exception. How difficult or challenging they may be depends on the type of seahorses you have. Two main factors determine how easy or hard seahorse fry are to raise: (1) their size at birth and (2) whether or not they undergo a prolonged pelagic phase. The bigger and better developed the newborns are, the easier they are to raise. Seahorse fry whose average length at birth is 10 mm (0.4 inches) or more are able to take enriched Artemia as their first foods and are relatively easy to rear. Seahorse fry that are significantly smaller than 10 mm (0.4 inches) at birth need to be started on smaller foods that are more difficult to provide in copious amounts on a daily basis, such as rotifers, copepods, and larval Mysis, making them more difficult to raise. Likewise, seahorse fry that undergo an extended pelagic phase, during which they drift freely with the plankton, are much more troublesome to raise than benthic seahorse fry, which orient to the substrate and seek out hitching posts straightaway. The pelagic fry are difficult because the surface huggers tend to gulp air and suffer fatal buoyancy problems, and may even become entrapped by surface tension. As a result, most hobbyists find that mortality is very high during the pelagic phase.
The easiest seahorse fry to rear are therefore benthic fry that are large and well developed at birth. Dwarf seahorses or Pixies (Hippocampus zosterae) fall into this category, and indeed many hobbyists have closed the life cycle with zosterae. The most difficult seahorse fry to raise are relatively small and underdeveloped at birth, and must pass through a lengthy pelagic stage. Brazilian seahorse fry (Hippocampus reidi) are a good example of this category, and are notoriously difficult to raise.
Ocean Riders span the gamut in that regard, including both those species that are the easiest of all to raise and those that are the most difficult to rear, and everything in between. At the one extreme, there are Mo’Olios (Hippocampus fisheri), which produce very large broods of tiny fry that are barely 3-4 mm at birth and remain pelagic all their lives, even as adults. Mo’Olios are very challenging for even expert aquaculturists with state-of-the-art facilities to raise. Brazileros (H. reidi) and Gigantes (H. ingens) likewise have enormous broods of relatively small (6-7 mm) fry that undergo a rather protracted pelagic phase lasting weeks. The average hobbyist would still be hard-pressed to regularly raise any of their fry.
At the other extreme, there are Pixies (H. zosterae), which produce small broods of large, well-developed benthic fry that hitch from day one. Pixies are probably the easiest seahorses to rear, and no doubt more hobbyists have closed the life cycle with this species than all other seahorses combined. Most of the remaining Ocean Rider types (Mustangs, Sunbursts, Pintos, Fire Reds) produce fry that are fairly good sized (about 8-10 mm) and whose pelagic phase is fairly short (several days rather than weeks), and which are therefore intermediate in difficulty.
If you have Mustangs or Sunbursts (Hippocampus erectus), Sam, they will produce fry that are moderately difficult to raise. They will be able to eat newly hatched brine shrimp right away, but they will go through a pelagic phase lasting anywhere from several days to a week or two. The link below will take you to an article that discusses how to set up a basic nursery tank, simple feeding regimens, and rearing the fry in greater detail (Mustang babies are suitable for the "easy" rearing method outlined in the article):
If you contact me off list ([email protected]), Sam, I have a lot more information on rearing seahorses that I can send you, and once I know what species of seahorses you have, I will provide you with better information regarding which type of nursery and which foods for the newborns will produce the best results.
Best of luck with your new seahorses and their future progeny, sir!